This design pre-dates the digital clocks of the later Soyuz designs. It flew on one of the early Soyuz T spacecraft, which started as a military design in 1967 and went through a complete redesign in the late 70’s with a launch escape system and solar cells. This was the first spacecraft to ferry three astronauts in space suits (unlike the slapdash Vokshod space race entrant). Flight 10 of Soyuz T was the first manned pad abort as the rocket blew up on the pad; the launch escape tower pulled the astronauts away to safety at 20 G’s.

The clock module provides current Moscow time, preset announcement time, and a stopwatch. The stopwatch is used for the propulsion system engine burn timing, to make sure it burns for the calculated time to reach the mission trajectory.